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Abstract：
The heterogenicity of antimicrobial resistance genes described in clinically significant bacterial isolates and their potential role in reducing the efficacy of classically effective antibiotics pose a major challenge for global healthcare, especially in infections caused by Gram-negative bacteria. We analyzed 112 multidrug-resistant (MDR) isolates from clinical samples in order to detect high resistance profiles, both phenotypically and genotypically, among four Gram-negative genera (Acinetobacter, Escherichia, Klebsiella, and Pseudomonas). We found that 9.8% of the total selected isolates were classified as extensively drug-resistant (XDR) (six isolates identified as A. baumannii and five among P. pneumoniae isolates). All other isolates were classified as MDR. Almost 100% of the isolates showed positive results for blaOXA-23 and blaNDM-1 genes among the A. baumannii samples, one resistance gene (blaCTX-M) among E. coli, and two genetic determinants (blaCTX-M and aac(6\')-Ib) among Klebsiella. In contrast, P. aeruginosa showed just one high-frequency antibiotic resistance gene (dfrA), which was present in 68.42% of the isolates studied. We also describe positive associations between ampicillin and cefotaxime resistance in A. baumannii and the presence of blaVEB and blaGES genes, as well as between the aztreonam resistance phenotype and the presence of blaGES gene in E. coli. These data may be useful in achieving a better control of infection strategies and antibiotic management in clinical scenarios where these multidrug-resistant Gram-negative pathogens cause higher morbidity and mortality.
摘要：
在临床上重要的细菌分离株中描述的抗微生物耐药基因的异质性及其在降低经典有效抗生素功效方面的潜在作用对全球医疗保健构成了重大挑战。尤其是由革兰氏阴性菌引起的感染。我们分析了来自临床样本的112株多重耐药（MDR）分离株，以检测高耐药谱，表型和基因型，在四个革兰氏阴性属中(不动杆菌，埃希氏菌,克雷伯菌属,和假单胞菌）。我们发现，所有选定的分离株中有9.8％被归类为广泛耐药（XDR）（6株被鉴定为鲍曼不动杆菌，5株被鉴定为肺炎链球菌）。所有其他分离株被分类为MDR。在鲍曼不动杆菌样品中，几乎100%的分离株显示blaOXA-23和blaNDM-1基因阳性结果，大肠杆菌中有一个抗性基因(blaCTX-M)，和克雷伯菌中的两个遗传决定子（blaCTX-M和aac（6\'）-Ib）。相比之下,铜绿假单胞菌仅显示一个高频抗生素抗性基因(dfrA)，68.42％的分离株中存在。我们还描述了鲍曼不动杆菌中氨苄青霉素和头孢噻肟抗性与blaVEB和blaGES基因的存在之间的正相关关系，以及氨曲南抗性表型和大肠杆菌中blaGES基因的存在之间。这些数据可能有助于在这些多药耐药革兰氏阴性病原体导致更高的发病率和死亡率的临床情况下更好地控制感染策略和抗生素管理。
